Fifty-three closed lock cases of internal derangement of the temporomandibular joint (TMJ) were studied on the correlation between disk configuration at MR imaging and nine clinical parameters composed of opening degree, age, clicking and locking duration, visual analogue scale of pain (VAS), pain score, jaw dysfunction score, life activity limited score, and TMJ X-ray photo findings. Disk configuration and degree of anterior disk displacement were assessed on MR imaging in closed mouth position: the antero-posterior length of disk and the distance from condyle to anterior and posterior portion of disk were measured, respectively. Results were obtained as follows;
1. Duration of clicking and locking were not correlated with MR index except that there was a strong correlation between clicking duration and the distance from condyle to anterior portion of the disk at MR imaging.
2. Opening degree was related to the disk deformity and the access of posterior portion of the disk to condyle.
3. Disk configuration and degree of antrior disk displacemnt were not correlatd with TMJ pain, but jaw dysfunction was related to the disk deformity and the distance from posterior portion of the disk to condyle.
4. TMJ X-ray photo findings were not correlated with clicking duration (below 3 years), locking duration (below 30 weeks), opening degree and disk configuration at MR imging.
5. In evaluation of factors related to opening degree in 53 patients with closed lock by means of multiple regression analysis, age, locking and clicking duration, TMJ pain, life activiy limited score were more strongly correlated to opening degree than the others.
